FTXUI/include/ftxui/dom/node.hpp

// Copyright 2020 Arthur Sonzogni. All rights reserved.
// Use of this source code is governed by the MIT license that can be found in
// the LICENSE file.
#ifndef FTXUI_DOM_NODE_HPP
#define FTXUI_DOM_NODE_HPP

#include <memory>  // for shared_ptr
#include <vector>  // for vector

#include "ftxui/dom/requirement.hpp"  // for Requirement
#include "ftxui/dom/selection.hpp"    // for Selection
#include "ftxui/screen/box.hpp"       // for Box
#include "ftxui/screen/screen.hpp"

namespace ftxui {

class Node;
class Screen;

using Element = std::shared_ptr<Node>;
using Elements = std::vector<Element>;

/// @brief Node is the base class for all elements in the DOM tree.
///
/// It represents a single node in the document object model (DOM) and provides
/// the basic structure for layout and rendering.
/// It contains methods for computing layout requirements, setting the box
/// dimensions, selecting content, rendering to the screen, and checking the
/// layout status.
/// It typically contains child elements, which are also instances of Node.
///
/// Users are expected to derive from this class to create custom elements.
///
/// A list of builtin elements can be found in the `elements.hpp` file.
///
/// @ingroup dom
class Node {
 public:
  Node();
  explicit Node(Elements children);
  Node(const Node&) = delete;
  Node(const Node&&) = delete;
  Node& operator=(const Node&) = delete;
  Node& operator=(const Node&&) = delete;

  virtual ~Node();

  // Step 1: Compute layout requirement. Tell parent what dimensions this
  //         element wants to be.
  //         Propagated from Children to Parents.
  virtual void ComputeRequirement();
  Requirement requirement() { return requirement_; }

  // Step 2: Assign this element its final dimensions.
  //         Propagated from Parents to Children.
  virtual void SetBox(Box box);

  // Step 3: (optional) Selection
  //         Propagated from Parents to Children.
  virtual void Select(Selection& selection);

  // Step 4: Draw this element.
  virtual void Render(Screen& screen);

  virtual std::string GetSelectedContent(Selection& selection);

  // Layout may not resolve within a single iteration for some elements. This
  // allows them to request additionnal iterations. This signal must be
  // forwarded to children at least once.
  struct Status {
    int iteration = 0;
    bool need_iteration = false;
  };
  virtual void Check(Status* status);

  friend void Render(Screen& screen, Node* node, Selection& selection);

 protected:
  Elements children_;
  Requirement requirement_;
  Box box_;
};

void Render(Screen& screen, const Element& element);
void Render(Screen& screen, Node* node);
void Render(Screen& screen, Node* node, Selection& selection);
std::string GetNodeSelectedContent(Screen& screen,
                                   Node* node,
                                   Selection& selection);

}  // namespace ftxui

#endif  // FTXUI_DOM_NODE_HPP